July 2007 - tz - lists.iana.org

How to support such capabilites based on current Olson Time Zone implementation
by Martin Dong July 27, 2007

July 27, 2007

Dear All in this maillist, We have been investigating the feasibility of migrating Olson Time Zone Database to our system. Given that our system is Linux-based, we can just use tzcode implementation or Glibc functions because Glibc has adopted Olson implementation to some extent. But according to our basic and existing requirements, I have met some problems that I think are hard for me: - How to get the local time of different region or city at the same time? The basic requirement is to display the local time of different region or city at the same time. After some study of Olson implementation, I knew function "localtime" will handle everything, parsing tzfile and doing the conversion from utc to local time. The correct local time can be gotten through a simple invocation to "localtime". But "localtime" assumes the Sytem Local Time Zone is set in environmental variable "TZ" or from the Standard TimeZone file "/etc/localtime" if "TZ" is not defined in the process. In this case, how can a caller get the local time of some city which is not the System Local Time Zone? It seems we must change "TZ" or the Standard TimeZone file before calling "localtime" to get another city's local time because "localtime" doesn't take such an argument that can let caller specify a time zone, which means "localtime" can return the local time related to either the System Local Time Zone or the time zone user specifies. Although I know there're so many applications which already integrates the Olson Database and they have realized my above requirement "display multiple local time at the same time", I don't know how they make it. - How to get the notification of DST status change as time elaspes? This problem is out of our another requirement that we need to inform other components in our system of the DST status change in various conditions, such as changing time may lead to DST change, changing local time zone may lead to DST change, and as time elapsing, etc. The former two behaviors are user-active ones, we can track the change easily, but the problem is the last one, it's the system automatic behavior, our of the control of user. In this case, the system needs some CALLBACK ability to capture this change and further broadcast it. For our system, there's an Alarm Server that can provide timer machinasm. We will parse our own time zone database and get the next nearest DST transition time and add it to Alarm Server, then when the timer is time out, Alarm Server will trigger a CALLBACK function to further process. But it seems Olson is lack of such capability. After thinking from another perpsective, if we can get the next nearest DST transition time through Olson Time Zone database, we can still utilize our current Alarm Server. But it's still a problem how to get the next nearest DST transition time through the current Olson implementation because all the implementation is hiden behind "localtime". In all the public functions, there's no such one which can support getting the DST transition time. I don't have any good idea in mind right now. Should I make some modification to Olson to add such capability, or other way i could go? I will very much appreciate if any of you can give me some hints about above problems. Thank you in advance. Best Regards, -Martin

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FW: Timezone of America/Tegucigalpa is wrong
by Olson, Arthur David (NIH/NCI) [E] July 23, 2007

July 23, 2007

I'm forwarding this message from Freek de Kruijf, who was not on the time zone mailing list at the time it was sent. Freek has since been added. --ado -----Original Message----- From: Freek de Kruijf [mailto:f.de.kruijf@hetnet.nl] Sent: Sunday, July 22, 2007 3:38 To: tz(a)lecserver.nci.nih.gov Subject: Timezone of America/Tegucigalpa is wrong L.S. The timezone of America/Tegucigalpa includes a Daylight Saving Time. This is wrong. See http://en.wikipedia.org/wiki/Honduras . It is only UTC-6. I can confirm this, while I am there. -- fr.gr. Freek de Kruijf

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Olson tz database tests
by Kevin July 23, 2007

July 23, 2007

Hi, is there an existing suite of tests (e.g. unit tests, regression tests, etc.) for the Olson time zone database (to ensure validity, completeness, etc.)? I'm more interested in the logic than the language, although I would prefer C/C++, C#, or Java. Thanks, Kevin

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More daylight savings in Australia
by Eric Ulevik July 23, 2007

July 23, 2007

The states of NSW, Victoria, ACT, Tasmania plan to harmonize DST, starting October 2007. "Under the plan, clocks will go forward one hour on the first Sunday in October, instead of on the last Sunday, and will be wound back by an hour on the first Sunday in April, rather than on the last Sunday in March." http://www.news.com.au/story/0,23599,21549128-2,00.html Regards, Eric Ulevik

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Timezone of America/Tegucigalpa is wrong
by Freek de Kruijf July 22, 2007

July 22, 2007

L.S. The timezone of America/Tegucigalpa includes a Daylight Saving Time. This is wrong. See http://en.wikipedia.org/wiki/Honduras . It is only UTC-6. I can confirm this, while I am there. -- fr.gr. Freek de Kruijf

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Re: Geographical boundaries for the continental US tz zones
by rlaw＠nc.rr.com July 18, 2007

July 18, 2007

----- Original Message ----- From: Paul Eggert <eggert(a)CS.UCLA.EDU> > I send my comments to your US timezone map directly to the TZ list > since I > think it could be of common interest in the list and also to urge > members to > send comments where appropriate. I've put all of my findings about the limits of U.S. time zones (past and present) online at http://www.statoids.com/tus.html. It's all verbal description. For example: > * Idaho county split (Idaho state) > I have a northern and southern part of Idaho county, which I got from > another timezone map (possibly Manifold map). This indicates that the > southern part of Idaho county is on America/Boise time while the > northernpart is on America/Los_Angeles. I have "Idaho county north of the Salmon River" on Pacific Time. > * Sioux county North Dakota > Tz database states "part of Sioux county" and that is exactly what > you have > included, splitting it around Latitude 46 Longitude -101.34. Where > did you > get shis from? I have included all Sioux county being on same time, > but that > most be wrong. I have "Sioux county west of ND route 31" on Mountain Time. Gwillim Law

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Daviess, Dubois, Knox, Martin and Pike counties jump thru 1 more hoop
by Paul Eggert July 18, 2007

July 18, 2007

The DOT yesterday announced a proposed rule that would move the 132,000 residents of Daviess, Dubois, Knox, Martin and Pike counties in Indiana back to Eastern time, effective November 4 (when DST ends this year). The proposed rule has a 30-day public comment period, and then must be approved by the DOT to become final. See the AP article on this subject at <http://www.indystar.com/apps/pbcs.dll/article?AID=/20070718/LOCAL/707180456…>.

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FW: Implementation of zoneinfo (Olson, tz) database in .NET c-sharp csharp
by Olson, Arthur David (NIH/NCI) [E] July 18, 2007

July 18, 2007

I'm forwarding this message from Joshua Kifer, who is not on the time zone mailing list. Those of you who are on the time zone mailing list should direct replies appropriately. --ado From: Joshua Kifer [mailto:joshua@jotts.com] Sent: Wednesday, June 20, 2007 8:33 PM To: tz(a)lecserver.nci.nih.gov Subject: Implementation of zoneinfo (Olson, tz) database in .NET c-sharp csharp I finally found an implementation of this at CodePlex. It's part of the PublicDomain project. http://www.codeplex.com/publicdomain I hope this post adds some search fodder to the interweb for all those unlucky bastards seeking (and not finding) the same.

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Geographical boundaries for the continental US tz zones
by Paul Eggert July 18, 2007

July 18, 2007

Jesper Norgaard Welen tried to send the following email to the list on July 1, but apparently didn't get through. I am enclosing it in the hopes that it does get through this time. From: Jesper Norgaard Welen [mailto:jnorgard@prodigy.net.mx] Sent: Domingo, 01 de Julio de 2007 16:15 To: 'tz(a)elsie.nci.nih.gov' Cc: 'emuller(a)adobe.com' Subject: RE: Geographical boundaries for the continental US tz zones Hello, Eric Muller I send my comments to your US timezone map directly to the TZ list since I think it could be of common interest in the list and also to urge members to send comments where appropriate. My newest map for World Time Explorer you can download from http://worldtimeexplorer.com/tztables.zip * Navajo/Hopi reservations There is an important Hopi population that you have not included around Latitude 36.14 Longitude -109.40 that I would recommend you to include (see WTE map) * Nevada on Idaho time The city Jackpot in Nevada (and several others like Owyhee and Mountain city) are on Idaho south time, or Denver time if you will. I have included it in a 25 km broad strip of northern Elko county, however just based on common sense when there were cities 12 km below the border that were on Denver time, and I would not expect their time to stop 100 meters outside the city boundary, but note that it is arbitrary, and quite possibly not quite 25 km. Jackpot itself is quite close to the border to Idaho. * Idaho county split (Idaho state) I have a northern and southern part of Idaho county, which I got from another timezone map (possibly Manifold map). This indicates that the southern part of Idaho county is on America/Boise time while the northern part is on America/Los_Angeles. Note that this is *not* documented in the tz database - I am still a bit ambivalent which one to believe. If you want pure tz database functionality, the timezone border should be a little further south. * Alaska I have the same doubts as you. However, I have implemented a solution, however arbitrary it is, seems much better than just putting Juneau for all of Alaska. The Nome area is small, while most of northwestern Alaska is set to Anchorage time. Then there is a Yakutat area and a Juneau area. They are all based on counties in this area. Comments are welcome. * America/Kentucky/Louisville This city belongs to Jefferson county of Kentucky, so I just assumed that this would comprise the Louisville timezone - however tz database needs to describe this - and include more counties if there are more. It just states the vague "part of Kentucky". * Sioux county North Dakota Tz database states "part of Sioux county" and that is exactly what you have included, splitting it around Latitude 46 Longitude -101.34. Where did you get shis from? I have included all Sioux county being on same time, but that most be wrong. * Cherry county Nebraska I see you have a different, more detailed split of Cherry county than mine. Where did you get this from? * Morgan county, Tennessee I recently discovered that this county is on CST/CDT, and included this in the western part of Tennesse. It's around Latitude 36.07 Longitude -84.56 * Alabama Note that (parts of) Chambers, Lee and Russell counties should be on America/New_York time, not on America/Chicago time. * Culberson county, Texas Note that the parts of this county including Nickel creek and Pine Springs are on America/Denver time. Regards, - Jesper Nørgaard Welen -----Original Message----- From: Eric Muller [mailto:emuller@adobe.com] Sent: Domingo, 01 de Julio de 2007 12:07 To: tz(a)lecserver.nci.nih.gov Subject: Re: Geographical boundaries for the continental US tz zones I have completed a first version of a map of the TZ timezones in the US. It is available as a shapefile at <http://www.efele.net/maps>. Comments welcome, Eric.

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Geographical boundaries for the continental US tz zones
by Eric Muller July 18, 2007

July 18, 2007

I am trying to figure out the geographical extent of the 19 continental US timezones defined by tz. Because my goal is ultimately to create a freely available digital map, I would like to get definitions in terms existing, freely available digital maps, and the ones at nationalatlas.gov seem appropriate. Specifically, I plan to use countyp020 (county boundaries 2001), statesp020 (states) and timeznp020 (time zones) [see below for more details on those maps]. I tried to translate the comments in the "northamerica" file in terms of operations on the elements of those three maps, but I have a few questions/comments. 1. I would think that America/Boise, America/Denver and America/Phoenix together correspond exactly to the Mountain time zone of timeznp020. However, the later includes the southern quarter of Idaho County, Idaho, while northamerica suggests that this county is entirely in America/Pacific. Who is right? 2. The description of America/Denver includes "far eastern Oregon", and the description of America/Boise includes "eastern Oregon". Comparing with timeznp020, I suspect that America/Denver should not include "far eastern Oregon". (and if timeznp020 is right, "eastern Oregon" could be better described as "most of Malheur County, Oregon"). 3. What does America/Indiana/Indianapolis cover? Is it all the counties of Indiana not listed in any of the other zones? 4. The overall description of Indiana includes: # - Daviess, Dubois, Knox, Martin, Perry, and Pulaski counties # have been like America/Indiana/Vincennes. # # - Crawford, Pike, Starke, and Switzerland counties have their own time zone # histories as noted below. However, it seems that Pulaski now has it own zone (America/Indiana/Winamac), so it should probably be moved from the first to the second bullet in the quote above. 5. The description of America/Indiana/Marengo is that it covers the eastern part of Crawford County. How is that county divided, and in which zone does the western part fall? 6. What part of Kentucky goes in America/Kentucky/Louisville? At this point, I am not trying to handle border towns such as West Wendover, mostly because I have no idea of where to find a boundary for such towns. Any suggestion on what to do for those cases is welcome. For those of you who are curious about the content of the maps cited above: you can download them from <http://nationalatlas.gov/atlasftp.html> and visualize them using standard GIS tools (I use the freely available OpenJUMP and uDig). Alternatively, I have created a KML version of timeznp020 (using org2ogr) and placed it at <http://efele.net/timeznp020.zip> (4MB, 15MB uncompressed); you can visualize it in Google Earth (File->Open); I assume that the built-in 1st level and 2nd level admin regions (under "borders") are close enough to statesp020 and countyp020. Below is my current recipe to build my map in terms of operations in the source maps. Comments welcome. Thanks, Eric. --- Phoenix timeznp020/(Mountain & no DST) Boise statesp020/(Idaho+Oregon) intersected with timeznp020/Mountain North_Dakota/Center countyp020/(Oliver County, North Dakota) North_Dakota/New_Salem countyp020/(Morton County, North Dakota) Indiana/Marengo countyp020/(Crawford County, Indiana) // should only be the eastern part of Crawford County? where is the // limit? where does the western part go? Indiana/Vincennes countyp020/(Daviess, Dubois, Knox, Martin, and Perry Counties, Indiana) Indiana/Petersburg countyp020/(Pike County, Indiana) Indiana/Knox countyp020/(Starke County, Indiana) Indiana/Winamac countyp020/(Pulaski County, Indiana) Indiana/Vevay countyp020/(Switzerland County, Indiana) Kentucky/Louisville countyp020/(Clark, Floyd, and Harrison counties, Indiana) // what part of Kentucky is in this zone? Kentucky/Monticello countyp020/(Wayne County, Kentucky) Indiana/Indianapolis ? // statesp020/Indiana minus what is already covered above minus // Dearborn and Ohio County (they are in America/New_York) and // minus Gibson, Jasper, Lake, LaPorte, Newton, Porter, Posey, // Spencer, Vanderburgh, // and Warrick counties (they are in America/Chicago) Menominee countyp020/(Dickinson, Gogebic, Iron, and Menominee Counties, Michigan) Detroit statesp020/Michigan minus what is already covered above Los_Angeles timeznp020/Pacific minus what is already covered above Denver timeznp020/Mountain minus what is already covered above Chicago timeznp020/Central minus what is already covered above New_York timeznp020/Eastern minus what is already covered above ----

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